I urval från Stockholms universitets publikationsdatabas

• The Role of Oxytocin Pathway Genes and Intranasal Oxytocin in Brain Structure and Connectivity: Insights into Neural Mechanisms

  2025. Shanshan Xiao.

  Avhandling (Dok)

  Oxytocin is a neuropeptide that plays a crucial role in human physiology and social behavior. However, the neurobiological mechanisms underlying the influence of oxytocin pathway gene variations and intranasal oxytocin on neural structure and connectivity remain unclear. This thesis set out to explore these mechanisms, aiming to deepen our understanding of how oxytocin influences brain structure, resting-state functional connectivity, and social function.

  Study I examined the associations between variations in ten single nucleotide polymorphisms (SNPs) within three oxytocin pathway genes and whole-brain gray matter volume using data from the UK Biobank (N ≈ 30,000 subjects of relevance for the current studies). The results indicated that carriers of the AA or AG genotypes of the oxytocin receptor gene rs237851 SNP had significantly larger hippocampal volumes compared to carriers of the GG genotype. These findings support a link between variations in the oxytocin receptor gene and hippocampal structure, which may have implications for social-cognitive functions, such as social recognition memory.

  Study II investigated the relationship between variations in ten SNPs in oxytocin pathway genes and resting-state functional connectivity among 55 independent components, again using data from the UK Biobank (N ≈ 30,000 subjects of relevance for the current studies). Findings revealed that individuals with the GG genotype at rs4813627 within the oxytocin structural gene (OXT) exhibited weaker resting-state functional connectivity in the corticostriatal circuit compared to those with the GA/AA genotypes. The GG genotype has been empirically linked to a behavioral tendency of insensitivity to others, providing insight into the neural mechanisms by which oxytocin-related genetic factors influence social behavior.

  Study III explored the effects of intranasal oxytocin on resting-state functional connectivity, focusing on regions densely populated with oxytocin receptors. The study tested whether connections between oxytocin receptor-enriched regions (e.g., thalamus, pallidum, caudate nucleus, putamen, and olfactory bulbs) and other brain regions responded to intranasal oxytocin administration, and whether these effects varied with age. Results showed age-dependent effects of intranasal oxytocin on resting-state functional connectivity. In young participants, oxytocin decreased connectivity density and strength in the thalamus, whereas in older participants, it increased connectivity density and strength in the caudate. These findings highlight the age-dependent mechanisms of exogenous oxytocin on brain function.

  Overall, this thesis explores the potential neurobiological mechanisms by which oxytocin pathway gene variations and intranasal oxytocin may influence brain structure and resting-state functional connectivity. These studies provide preliminary evidence on how oxytocin might affect social functions, offering insights for future research in neuropsychology and potential directions for interventions targeting social cognitive disorders.

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• Associations between genetic variations in oxytocin pathway genes and hippocampal volume: Insights from the UK Biobank

  2025. Shanshan Xiao (et al.). Cortex 183, 211-219

  Artikel

  The role of oxytocin-related genes in social-cognitive function has been previously established, but structural brain mechanisms underlying this link remain poorly understood. Utilizing a substantial dataset from the UK Biobank (N ≈ 30,000), this research determined associations between variations in ten single nucleotide polymorphisms (SNPs) within three oxytocin pathway genes (i.e., the oxytocin/neurophysin I prepropetide gene, the cluster of differentiation 38 glycoprotein gene, the oxytocin receptor gene) and whole-brain gray matter volume. Carriers of the AA or AG genotypes of the oxytocin receptor gene rs237851 SNP exhibited significantly larger hippocampal volume than carriers of the GG genotype. These results support the link between variations in the oxytocin receptor gene and hippocampal structure, with possible impact on social-cognitive function such as social recognition memory.

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• Oxytocin pathway gene variation and corticostriatal resting-state functional connectivity

  2024. Shanshan Xiao (et al.). Comprehensive Psychoneuroendocrinology 20

  Artikel

  Genetic variations in single nucleotide polymorphisms (SNPs) within oxytocin pathway genes have been linked to social behavior and neurodevelopmental conditions. However, the neurobiological mechanisms underlying these associations remain elusive. In this study, we investigated the relationship between variations of 10 SNPs in oxytocin pathway genes and resting-state functional connectivity among 55 independent components using a large sample from the UK Biobank (N ≈ 30,000). Our findings revealed that individuals with the GG genotype at rs4813627 within the oxytocin structural gene (OXT) exhibited weaker resting-state functional connectivity in the corticostriatal circuit compared to those with the GA/AA genotypes. Empirical evidence has linked the GG genotype at OXT rs4813627 with a behavioral tendency of insensitivity to others. These results inform the neural mechanisms by which oxytocin-related genetic factors can influence social behavior.

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• Age-dependent effects of oxytocin in brain regions enriched with oxytocin receptors

  2024. Shanshan Xiao (et al.). Psychoneuroendocrinology 160

  Artikel

  Although intranasal oxytocin administration to tap into central functions is the most commonly used non-invasive means for exploring oxytocin’s role in human cognition and behavior, the way by which intranasal oxytocin acts on the brain is not yet fully understood. Recent research suggests that brain regions densely populated with oxytocin receptors may play a central role in intranasal oxytocin’s action mechanisms in the brain. In particular, intranasal oxytocin may act directly on (subcortical) regions rich in oxytocin receptors via binding to these receptors while only indirectly affecting other (cortical) regions via their neural connections to oxytocin receptor-enriched regions. Aligned with this notion, the current study adopted a novel approach to test 1) whether the connections between oxytocin receptor-enriched regions (i.e., the thalamus, pallidum, caudate nucleus, putamen, and olfactory bulbs) and other regions in the brain were responsive to intranasal oxytocin administration, and 2) whether oxytocin-induced effects varied as a function of age. Forty-six young (24.96 ± 3.06 years) and 44 older (69.89 ± 2.99 years) participants were randomized, in a double-blind procedure, to self-administer either intranasal oxytocin or placebo before resting-state fMRI. Results supported age-dependency in the effects of intranasal oxytocin administration on connectivity between oxytocin receptor-enriched regions and other regions in the brain. Specifically, compared to placebo, oxytocin decreased both connectivity density and connectivity strength of the thalamus for young participants while it increased connectivity density and connectivity strength of the caudate for older participants. These findings inform the mechanisms underlying the effects of exogenous oxytocin on brain function and highlight the importance of age in these processes.

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• Regional differences in personalities account for substantial heterogeneity of loneliness change from before to during the COVID-19

  2023. Shanshan Xiao, Junhua Dang. Frontiers in Psychology 14

  Artikel

  Ernst et al. (2022) recently reported a strictly conducted meta-analysis investigating whether people's loneliness increased during the COVID-19 pandemic relative to prepandemic times. Based on 19 longitudinal studies that tracked the change of participants' loneliness scores, their main analysis found a small effect size, Hedge's g = 0.23 (see Supplementary Table S1for a summary of the main information extracted from these articles). However, the heterogeneity between individual studies was very high, I2 = 98%, which means most differences observed between individual studies were due to real differences in effect sizes rather than random sampling errors. Although a series of factors have been considered (e.g., sample type and age) to account for the between-effects heterogeneity, none of them showed significant moderation, leaving the heterogeneity unanswered. Given the included studies were conducted in different countries, in this article we suggest that regional differences in the Big-Five personalities should be considered because loneliness has been strongly associated with personalities (Buecker et al., 2020) and people's personalities vary across countries (McCrae, 2001). Therefore, we test whether regional differences in the Big-Five personalities could account for the observed between-effects heterogeneity in Ernst et al.'s (2022) meta-analysis.

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• Collectivism reduces objective mobility trends to public areas during the COVID-19 pandemic

  2022. Junhua Dang, Shanshan Xiao. Frontiers in Public Health 10

  Artikel

  In order to slow down the spread of the coronavirus, staying at home and avoiding going outside have been either strongly recommended or stringently enforced by governments all over the globe. Previous studies found that people with more collectivist orientation were more willing to comply with governmental guidelines and engage in preventive behaviors such as social distancing. However, these studies were based on self-report data within a short period. The current study aims to overcome these limitations by using objective mobility data generated by Google users all over the world during the past two years, thus providing a stronger test for the predictive effect of collectivism on preventive measures in response to the pandemic. We found consistent results at both the US state level (n = 50) and the country/territory level (n = 133), such that people in more collectivistic regions reduced their visits to and length of stay at certain public areas such as parks during the past two years. Our findings emphasize the importance of cultural values in face of global crises.

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• The Beauty of the Zero

  2021. Junhua Dang (et al.). Social Psychology and Personality Science 12 (4), 544-549

  Artikel

  Unlike the presentation format in a typical delay discounting task (e.g., Would you prefer [A] US$4.3 today OR [B] US$7.5 in 22 days?), Magen et al. inserted a zero to each alternative (e.g., Would you prefer [A] US$4.3 today and US$0 in 22 days OR [B] US$0 today and US$7.5 in 22 days?) and found this manipulation effectively reduced delay discounting (d= .84), which was referred to as the hidden-zero effect. Study 1 was a direct replication of this effect. In Study 2, we tested whether the explicit-zero format could buffer against the detrimental effect of exposure to sexy cues on delay discounting. In Study 3, we explored the mechanism underlying the hidden-zero effect. Taken together, the hidden-zero effect was consistently found across all studies (N= 2,440) and our internal meta-analysis yielded a medium to large effect size (d= .52).

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• Intranasal Oxytocin and Response Inhibition in Young and Older Adults

  2017. Diana Cortes (et al.).

  Konferens

  In normal aging, people are confronted with impairment in both socioemotional and cognitive abilities. Specifically, there are age-related declines in inhibitory processes that regulate attention towards irrelevant material. In last years, the intranasal administration of the neuropeptide oxytocin has mainly been related to improvements in several domains such as emotion recognition and memory, but to date the effects of oxytocin in aging remain largely unknown. In a randomized, double blind, placebo controlled, within-subjects study design, we investigated whether oxytocin facilitates inhibitory processing in older adults compared to younger adults. In total, 41 older adults (51% women; age range 65-75 years) and 37 younger adults (49% women; age range 20-30 years) participated in this study two times, receiving a single intranasal dose of 40 IU of placebo and oxytocin in randomized order 45 minutes before engaging in the task. Participants were tested approximately a month apart and mostly at the same hour during both occasions. Inhibition was measured with a Go/NoGo task which included happy and neutral faces as targets (Go stimuli) and distractors (NoGo stimuli) shown on a computer screen. Participants were instructed to press a button any time they saw a target and remain passive when encountering a distractor. Preliminary results indicate effects for happy and neutral faces, but only in the distractor condition. For happy distractors, women rejected correctly happy faces more accurately than men did, both in the placebo and oxytocin conditions. A main effect of age was observed for the neutral distractors, where older adults were more successful in inhibiting responses than younger adults during oxytocin and placebo treatments. We did not observe effects of oxytocin in the different tasks. The role of oxytocin was not clear distinguished in the tasks. In sum, our findings showed that age and gender can influence inhibition but their effects depend on the displayed emotions. This suggests that the ability to inhibit interfering distractors may remain intact despite of age and that deficits in inhibition may be selective. The role of oxytocin in inhibition needs to be further investigated since it is possible that it is context dependent.

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• Individual differences in dopamine level modulate the ego depletion effect

  2016. Junhua Dang (et al.). International Journal of Psychophysiology 99, 121-124

  Artikel

  Initial exertion of self-control impairs subsequent self-regulatory performance, which is referred to as the ego depletion effect. The current study examined how individual differences in dopamine level, as indexed by eye blink rate (EBR), would moderate ego depletion. An inverted-U-shaped relationship between EBR and subsequent self regulatory performance was found when participants initially engaged in self-control but such relationship was absent in the control condition where there was no initial exertion, suggesting individuals with a medium dopamine level may be protected from the typical ego depletion effect. These findings are consistent with a cognitive explanation which considers ego depletion as a phenomenon similar to switch costs that would be neutralized by factors promoting flexible switching.

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• When the poor excel

  2016. Junhua Dang (et al.). Scandinavian Journal of Psychology 57 (4), 288-291

  Artikel

  Recent research has shown that poverty directly impeded cognitive functions because the poor could be easily distracted by monetary concerns. We argue that this effect may be limited to functions relying on working memory. For functions that rely on proceduralized processes however, monetary concerns elicited by reminding of financial demands would be conducive rather than harmful. Our results supported this hypothesis by showing that participants with lower income reached the learning criterion of the information-integration categorization task faster than their more affluent counterparts after reminding of financial demands.

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